1. Field of the Invention
The present invention relates to resettable circuit interrupting devices and systems which includes ground fault circuit interrupters (GFCI's), arc fault circuit interrupters, immersion detection circuit interrupters, appliance leakage circuit interrupters, circuit breakers, contactors, latching relays and solenoid mechanisms. More particularly, the present invention relates to a method and apparatus for resetting and testing such devices which are capable of being “locked out” such that the device cannot be reset if the device becomes non-operational or if an open neutral condition exists.
2. Description of Related Art
The electrical wiring device industry has witnessed an increasing need for circuit breaking devices which are designed to interrupt power to various loads, such as household appliances, consumer electrical products and branch circuits. In particular, electrical codes require electrical circuits in home bathrooms and kitchens to be equipped with ground fault circuit interrupters. Presently available GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894 (the “'894 patent”) use a trip mechanism to mechanically break an electrical connection between one or more input and output conductors. Such devices are resettable after they are tripped by, for example, the detection of a ground fault. In the device of the '894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the connection between input and output conductors) includes a solenoid or trip coil. A test button is used to test the trip mechanism and circuitry used to test for faults, and a reset button is used to reset the electrical connection between input and output conductors.
However, instances may arise where an abnormal condition, caused by, for example, a lightening strike occurs which may result not only in a surge of electricity at the device but also a disabling of the trip mechanism used to cause the mechanical breaking of the circuit. This may occur without the knowledge of the user. Under such circumstances an unknowing user, faced with a GFCI which has tripped, may press the reset button which, in turn, will cause the device with an inoperative trip mechanism to be reset without the ground fault protection available.
Further, an open neutral condition, which is defined in Underwriters Laboratories (UL) Standard PAG 943A, may exist with the electrical wires supplying electrical power to such GFCI devices. If an open neutral condition exists with the neutral wire on the line (verses load) side of the GFCI device, an instance may arise where a current path is created from the phase (or hot) wire supplying power to the GFCI device through the load side of the device and a person to ground. In the event that an open neutral condition exists, current GFCI devices which have tripped, may be reset even though the open neutral condition may remain.
The device described in commonly owned U.S. Pat. No. 6,040,967, ('967) relates to resettable circuit interrupting devices, such as but not limited to GFCI devices, that include a reset lock-out mechanism which prevents the resetting of electrical connections or continuity between input and output conductors if the circuit interrupter used to break the connection is non-operational or if an open neutral condition exists. In this device, both the test button used to test the trip mechanism and circuitry used to sense faults, and the reset button used to reset the electrical connection between input and output conductors requires electrical power to operate an electrical component. A GFCI that can be tripped manually without requiring electrical power is desirable.